PHASE II DESIGN 1981-1989 · BLOCK II SATELLITES Rockwell International Selective Availability and Anti-Spoof (Y-Code) Implemented Constellation downsized to 21 satellites(6 planes) av message slightly modified OPERATIONAL CONTROL SEGMENT Monitors at Ascension, Diego Garcia, Guam, Hawaii, and 24-satellite ephemeris(orbit)determination PHASE II/PHASE III USER EQUIPMENT Rockwell Collins, Magnavox and Teledyne Systems Rockwell Collins and Magnavox · Rockwell collins 卫星定位技术与方法—袁林果 2005225(17 GPS Segments Space segment position constants Monitor User segment Control segment 卫星定位技术与方法—袁林果 20052-25(189 卫星定位技术与方法——袁林果 2005-2-25 17 • BLOCK II SATELLITES • Rockwell International • Selective Availability and Anti-Spoof (Y-Code) Implemented • Constellation downsized to 21 satellites (6 planes) • Nav message slightly modified • OPERATIONAL CONTROL SEGMENT • Monitors at Ascension, Diego Garcia, Guam, Hawaii, and Colorado Springs • 24-satellite ephemeris (orbit) determination PHASE II DESIGN 1981-1989 • PHASE II/PHASE III USER EQUIPMENT • Rockwell Collins, Magnavox and Teledyne Systems • Rockwell Collins and Magnavox • Rockwell Collins 卫星定位技术与方法——袁林果 2005-2-25 18 GPS Segments